The human ankle joint is capable of a wide range of motion. Such motion includes dorsiflexion (moving the foot upwardly), plantarflexion (moving the foot downwardly), adductor (moving the foot inwardly toward the midline of the body) and abductor (moving the foot outwardly away from the midline of the body). Because the ankle joint supports the entire weight of the body during upright movement, it is, at times, subjected to severe stresses that can cause injury. This can occur while working, while performing day-to-day activities and especially during athletic activity. Due to such circumstances, ankle joint injuries are among the most common injuries suffered.
Moreover, the ankle joint plays an important role in maintaining balance. As individuals age and/or deteriorate due to disease, the ankle joint is commonly affected. This, in turn, compromises the individual's ability to keep their balance and places the individual at serious risk of suffering a harmful fall.
Medical treatment of an injury to the ankle joint (such as a sprain, strain or break) commonly entails immobilization of the soft tissues that encompass the joint. In fact, the muscles, ligaments, and tendons of the joint are often immobilized for a sufficient period of time thereby causing them to become weakened or atrophied. Thus, after the initial and pain swelling associated with the acute injury has diminished, it is important to rehabilitate the ankle to restore stability, to restore range of motion, and to increase strength in the affected soft tissues of the ankle joint.
One way this can be accomplished is by exercising the muscles surrounding the ankle, lower leg and foot through a desired range of motion on a device that is capable of providing resistance to such movement. Indeed, a frequently neglected muscle group for exercise injury prevention and rehabilitation is the shin. The major muscles responsible for dorsiflexion (i.e., tibialis anterior and extension hallicusis longus) are all present in the shin area. Moreover, by strengthening the muscles in the lower leg and foot, one may significantly reduce the possibility of future ankle injuries. Additionally, by improving strength and range of motion, balance can be improved.
Many exercise devices have been taught in the art. The ability of the exercise device to provide resistance to the ankle through the full range of motion is especially important in strengthening the muscles in ankle, foot and especially the shin area. Several of these prior devices provide exercise only by ankle and/or foot movement or motion in one direction, or in a very limited number of directions. See, for example, U.S. Pat. No. 1,509,793 (Thompson), issued Sep. 23, 1924 (exercise apparatus for the feet having foot treadle whose movement is guided in a slightly curved up or down path while pivoting on ball joint); U.S. Pat. No. 5,897,464 (Mcleod), issued Apr. 27, 1999 (device for exercising the ankle that can pivot up or down or be rocked from side-to-side where the foot plate can also be rotated laterally to position the foot at different angles); U.S. Pat. No. 5,368,535 (Twardokens), issued Nov. 29, 1994 (weighted exercising device where the foot can be rotated laterally against resistance provided by a tensioned cable). As a result, these prior devices do not provide, for example, all of the dorsiflexion and plantarflexion motion, coupled with adductor and abductor motion necessary to exercise of the ankle throughout the full range of motion.
Many of these prior exercise or rehabilitation devices involve rocking on a ball-type joint and thus provide little, if any, resistance to movement of the ankle through its full range of motion. See U.S. Pat. No. 478,166 (Madsen), issued Jul. 5, 1892; U.S. Pat. No. 2,206,902 (Kost), issued Jul. 9, 1940; U.S. Pat. No. 4,186,920 (Fiore et al), issued Feb. 5, 1980; U.S. Pat. No. 4,199,137 (Giguere), issued Apr. 22, 1980; and U.S. Pat. No. 5,368,536 (Stodgell), issued Nov. 29, 1994. See also U.S. Pat. Nos. 5,536,226 and 5,667,462 (Gordon), issued Jul. 16, 1996 and Sep. 16, 1997, which disclose an exercise and physical therapy device for the foot and ankle that is pivoted about a single torsion device underneath the arch of the foot to provide up or down, or side-to-side rocking movement. Other devices are only directed at improving the balance and coordination of the user, rather than exercising a particular muscle or group of muscles in the ankle, foot or lower leg. See U.S. Pat. No. 3,134,591 (Conn et al), issued May 26, 1954, which discloses a rotatably mounted foot exercise device so that user can spin at a very high rate of speed to develop balance, skill and coordination.
Accordingly, there still remains a need for exercise devices to strengthen the muscles of the ankle, foot and lower leg, especially the shin, and particularly to provide resistance to the full range of motion of the ankle.